Flash lamp synchronizing device



May 25, 1937. E, WATSON 2,081,783

FLASH LAMP SYNCHRONIZING DEVICE Filed Jan. 10, 1936 2 Sheets-Sheet l Inventor: Estel l MWatSon by His Attorney.

May 25, 1937. WATSQN 2,081,783

FLASH LAMP swcmaomzma DEVICE Filed Jan. 10, 1936 2 Sheets-Sheet 2 swarm lnver-ltor'. Esta I LWatsofi,

Patented May 25, 1937 FLASH LAMP SYNCHRONIZING DEVICE Estell M. Watson, Cleveland Heights, Ohio, assignor to General Electric Company, a corporation of New York Application January 10, 1936, Serial No. 58,507

4 Claims. (Cl. 6729) My invention relates to photography and more particularly to apparatus for synchronizing a camera shutter with a light source.

The use of flashlamps of the type shown in 5 Reissue Patent 18,678, Ostermeier, granted December 6, 1932, where it is desired to take pictures with exposure times of the range of .01 of a second requires that the shutter be timed to use as much as possible of the available light.

Since the maximum of the flash is delayed approximately .02 to .03 of a second, it is necessary to have some kind of device which will delay the shutter by the same amount the flash is delayed after the closing of the lamp circuit. There are devices on the market at the present time which delay the shutter by about the same amount each time, without regard to the variation in the delay of the flash from the lamp caused by uncontrollable variations in manufacture. This results in occasional failure of 'the lamp and shutter to synchronize with the result that the negative is unsatisfactorily exposed.

It is evident that the most suitable means of adjusting the delay of the shutter to compensate for the variations in the delay of the flash from the lamps is to have the shutter controlled by the light from the lamp itself. Some work has been done along this line and the present invention is an advancement in the development of this type of apparatus.

One of the objects of my invention is to provide a synchronizing apparatus which will always open the camera shutter at the same time relative to the flash from the lamp. Another object 1 is to provide an apparatus-having a minimum number of parts so that it may operate rapidly and be operable with a minimum amount of energy.

One of the features'of my invention is the provision of a magnetic holding means which holds the shutter actuating mechanism in an inoperative position and is caused to release the said shutter actuating mechanism when the fiashlamp is energized or ignited. Further features and advantages of my invention will appear mechanism there Referring to Figs. 1 and 2, the control mechanism I0 is mounted adjacent the camera shutter so as to engage the shutter release lever l2. The control mechanism comprises a cable release |3 which is fastened to the top of the synchronizer box l4 and is arranged to push a rod or plunger l5 downward. Two collars l6, l1 are rigidly fastened to rod l5 and a sleeve or plunger IE on the lower end of rod I5 is allowed to move along the rod a short distance determined by the length of a slot H! in plunger H! which is engaged by a pin 20 on rod l5. There are coil springs 2 I, 22 on rod IS, the upper spring 2| bearing on collar I6 and on lug 23 on the wall of the box l4 and being used to return the said rod I5 and other mechanism to its normal position after a picture is taken. The lower spring 22 which bears on collar l1 and plunger I8 absorbs energy when rod I5 is pushed downward and releases it to propel the plunger l3 downward when it is allowed to move by being disengaged from the hook 24 on armature 25.

When a picture is to be taken, a button 26 on the shutter-release cable I3 is pressed. After the collar l6, which has an insulating washer 21 on its upper surface, has moved downwardly with plunger l5 a very short distance it allows leaf spring contact 28 to engage a contact 29. This closes a holding circuit including a battery 30 and the holding coil portion 3| of an electromagnet coil 32. This energizes the holding coil 3|, setting up enough flux in the core 33 to hold the armature 25 in contact therewith against the pull of a spring 34. In the normal position and until just after contacts 28, 2,3 are closed, the armature 25 is also held against the core 33 by a leaf spring 34' which bears on collar |'I. As the button 26 is further depressed, a flange 35 on plunger l8 comes to rest againstthe hook 24 on armature 25 as shown in dot-dash lines in Fig. 1. Additional movement of the button 26 brings it to the end of its travel when the collar I6 strikes a contact 36. This closes a circuit through a fiashlamp 31, the circuit also including a battery 38 and conductors 39, 40. The light flux from said lamp falls on a light-sensitive cell 4| causing its resistance to become so low that enough current is allowed to flow through the release coil portion 42 of the coil 32 so that the reduced flux will no longer maintain armature 25 against the core 33. When the armature 25 is pivoted on the pin 43 by the pull of spring 34, the hook 24 releases the plunger l8, allowing it to be forced downward against the shutter release lever l2. This trips the shuttentaking a picture at a time when'there is adequate light from the flashlamp 31. It is evident therefore that no variation in the time elapsed between closing the flashlamp circuit and 5 the actual flash will disturb the proper synchroniration of the flash and shutter. When the button 25 is released, the rod l5 returns to itsinitial position, opens the two circuits and leaves the armature 25 in position to take another picture after lamp 31 is replaced. If

the apparatus should operate too rapidly, a translucent shield 44 may be placed between the cell 4| and the flashlamp 31. The cell 4| may be of the type manufactured by the Weston Electrical Instrument Corporation of Newark, N. J

and known as Model 594.

The control mechanism l0 shown in Fig. 3 may be used with the circuit shown in Fig. 1 and differs from the control mechanism I 0 in Figs. 1 and 2 in that the springs 2| and 22 are tension springs rather than compression springs. The upper spring 2| is located between the lug 23 and the collar I1, while the lower spring 22 is located between the flange 35 on the plunger 13 and the lower end of the box l4. The hook 24 on the armature 25 is in this case made separate from the armature and is mounted in a slot in the lower end of said armature on a leaf spring 45. When the cable release button is pressed, the rod I5 is moved downward and the collar It allows the contact 28 to engage the contact 29, thereby closing the circuit to the holding portion 3| of the electro-magnet coil 32. Upon further downward movement of the rod, II the collar I 5 e 8 8es a contact 46 which in turn engages the contact 35 to close the circuit through the flashlamp 31. This causes sumcient flux to" be introduced into the core 33 through the release coil portion 42 in opposition to the flux induced by the holding coil portion 3| to allow the spring 34 to rotate the armature 25 about the pin 43.

The hook 24 is thereby pulled away from the flange 35 permitting the spring 22 to pull the 'l lunger l5 downward and actuate the shutter release lever 12.

. Figs. 4 and 5 show a modification used on a shutter ll having a priming lever 41 in addition to the release lever I2. The release lever 12 is pulled down by a spring 48 so as to be inoperative 50 which allows the priming lever to be moved up and down "at will. The downward movement of the priming lever 41 primes the shutter actuating mechanism and the-upward movement thereof opens and closes the shutter. To take a picture the priming lever 41 is first pushed down into engagement with lever 48 which is pushed over thereby so that it engages the finger or dog 50 extending from lever 41. In moving to this position, lever 49 is pivoted on pin 5| so that the contact 52 on the arm 53 thereon engages the contact 54 which closes the holding circuit of the device. The holding circuit comprises the battery 35, the coil 32 and the resistalnce 55. The coil 32 produces magnetic flux in the core 33 which attracts the armature 25 which is attached to the lever 49 and is held in the position shown by the flux in said core. The flashlamp 31 is now set oii by closing switch 55 which closes the circuit including the battery 33 and said lamp. The light given oi! falls upon the light-sensitive 3 cell 4|. which is connected across the coil 32 and reduces the flow or current therethrough, causinglthe armature 25 to fall. The movement of the armature turns lever49 so that it no longer engages-the dog 50, whereupon the priming lever ,41 swings upward and the shutter is operated.

The control mechanism is mounted on the box l4 to which spring 48 is attached by arm 51.

Fig. 6 shows an alternative wiring diagram to that shown in Fig. 5. In this arrangement, resistance 55 has been eliminated and the holding circuit arranged so as to include battery 30 and only a holding coil portion 31 of coil 32. The magnetic pull of the holding circuit on the arma- .ture 25 is reduced as before by the light flash,

causing the shutter to operate.

Fig. '1 shows another species of my invention which operates the camera shutter through the priming lever 41. The release lever I2 is held down so the priming lever can control all movements of the shutter. In this species the priming lever 41 is pushed down until it engages the tooth 58 of armature 25 which turns about pin 43 so that tooth 55 thereof engages the priming lever 41 as shown. The armature 25 is kept in this position by the magnetic attraction of a permanent magnet 80. In this position the armature also closes the circuit including the lightsensitive cell 41, the battery 30 and the coil 5| since the contact 52 on the arm 53 extending from said armature engages the contact 54. The flashlamp 31 is now set 01! by closing the circuit comprising as before the switch 55 and the battery 38 and the light given of! falls upon the light-sensitive cell 41, inducing a magnetic flux in the armature 25, located within coil 6i, which repels thatoi. the permanent magnet 50. The attraction of the permanent magnet 50 for the armature 25 is lessened so that spring 34 turns it about pin 43, carrying tooth 59 away from the priming lever 41. The said priming lever 41 then swings upward and the shutter is actuated.

Obviously the circuits and mechanisms shown and described may be variedwithout departing from the scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1, In an apparatus of the type described, the combination of aflashlamp, a camera shutter, means for actuating said shutter, magnetic means for holding said shutter-actuating means in an inoperative position, means for energizing said flashlamp, a light-sensitive cell disposed adjacent said fiashlamp, and an electrical circuit including said cell for repelling the magnetic flux in said holding means immediately after said flashlamp is energized and the light therefrom falls upon said light-sensitive cell thereby releasing said shutter-actuating means.

2. In an apparatus of the type described, the combination of a flashlamp, a camera shutter, means for actuating said shutter, an electromagnet for holding said shutter-actuating means in an inoperative position comprising a coil and a core, a source of current electrically connected to said coil, means for energizing said flashlamp, and a light-sensitive cell disposed adjacent said flashlamp and electrically connected to the coil of said electro-magnet whereby when the flashlamp is energized current is caused to how through said coil in the opposite direction to the current flow from said source of current/to reduce the magnetic flux in said core thereby releasing said shutter-actuating means.

3. In an apparatus of the type described, the

combination of a flashiamp, a camera shutter, a release lever on said shutter, a rod, 9. plunger slidably mounted on said rod and disposed ad- Jacent said release lever, a spring located between portions of said rod and plunger, an electro-magnet comprising a coil and a core, an electrical circuit including said coil and a source of current and contacts disposed adjacent said rod and adapted to be closed by movement of said rod, a second electrical circuit includingsaid fiashlamp and a source of current and a pair of contacts adjacent said rod and. adapted to be closed upon further movement of said rod; an armature adjacent said core and engaging said plunger, and a light-sensitive cell disposed adjacent the said fiashlamp, said cell being electrically connected to said coil of said electro-magnet whereby when said rod is moved said firstmentioned electrical circuit is closed to energize said electro-magnet and hold said armature thereagainst and' then said secondmentioned circuit is closed to energize said fiashlamp thereby causing current to flow through the coil of said electro-magnet in the opposite direction to the current flow from the source of current in: said first-mentioned circuit to reduce the magnetic flux in the core and thereby allow said armature to release said plunger and actuate the shutter-release lever.

4. In an apparatus of the type described, the combination of a fiashlamp, means for energizing said fiashlamp, a camera shutter, a shutter release lever, an armature'disposed adjacent to and in engagement with said lever, a magnet for holding said armature in engagement with said lever, a coil disposed adjacent said magnet, a light-sensitive cell disposed adjacent said flashlamp, and an electrical'circuit including a source of electrical energy and said cell and coil where by when said fiashlamp is energized and the light therefrom falls upon said light-sensitive cell a current is caused to flow through said coil and induce a' magnetic flux which repels that of the inagnet thereby releasing the said armature from its engagement with the said shutter-actuating lever.

ESTELL M. WATSON. 

